Steel and Sorrow: Rise of the Mercenary king - Chapter 8: Blood feud(2)

The journey to the martial peak is a lonely, solitary and long one. In the face of adversity, you must survive and remain unyielding. Only then can you break through and continue on your journey to become the strongest. Sky Tower tests its disciples in the harshest ways to prepare them for this journey. One day the lowly sweeper Kai Yang managed to obtain a black book, setting him on the road to the peak of the martials world.

Transform into Divine Dragon and dominate the world!
He is the only Divine Dragon in the sea who founded an underwater Dragon Palace.
With Crawfish Soldiers and Crab Generals as his followers, wild sharks and gigantic octopuses as his subordinates, he is the dragon that rules the city.

- Description from Novelupdates

After getting forcefully reincarnated into a world of an otome game he has no clue about, the protagonist is then killed and brought back to life by the prideful villainess with one desire.

To rule the world.

As the ruthless girl’s Eternal Servant, how will he dodge the fate that the game system has in store for him?

Young Master Lu says, “My wife knows nothing at all and has a bad temper. You’d better not bully her.” Gu Mang watches silently as this man warns everyone who comes his way.